A study will be made of the kinetics of ion transport through ultrathin (biological and artificial) membranes which will involve innovation in both theory and experimentation. A general theory unifying the continuum (Nernst-Planck) and single-barrier (Markin-Lauger) approaches is being worked out for carrier transport along the lines of our earlier work. A powerful general formalism for the description of small-amplitude perturbations of ion-permeable membranes is being refined. We will extend this to include the description of noise. We will further develop our high-frequency, computer-based pulse technique for the measurement of fast transients, and combine this with our Fourier Transform method in order to obtain precise data on the transient response of ionophores in membranes. A number of specific systems have been enumerated; these will be studied with the above-mentioned techniques. BIBLIOGRAPHIC REFERENCES: A unified approach to ion transport through membranes I. Membrane-soluble ions. R. de Levie and K.M. Abbey, J. Theoret. Biol. 56 (1976) 151-173. Electrochemistry of artificial ultrathin lipid membranes. A review. R. de Levie, J. Electroanal. Chem., 69 (1976) 265-297.